Method and apparatus for forming metal roll-formed parts

Abstract

Roll-formed parts having joggles or other non-linear bend lines are formed using a pair of forming mandrels having clamping surfaces with non-planar portions which are engaged on opposite sides of a sheet metal blank and passed between successive sets of forming rolls of a roll forming machine. As the mandrels and the blank enter a first roll forming pass, the mandrels and the blank are clamped together with sufficient pressure that the portions of the blank engaged by the mandrels are forced to conform to the shapes of the clamping surfaces. Parts of the blank are moved into engagement with other surfaces of at least one of the mandrels as the blank and the mandrels progress from pass to pass. Specially shaped rolls are provided to insure proper formation of the entire roll-formed part. The roll formed parts may be made from metal having a uniform thickness or different thicknesses.

Having described my invention, I claim: 
     
       1. The method of manufacturing an elongate roll-formed part from a flat metal blank using a roll forming machine constructed to roll-form said part by progressively bending said blank about bend lines, said machine having a series of passes along which the blank being formed is driven in a predetermined direction, said roll-formed part having at least one section having longitudinally-extending surface portions, said surface portions having mutually coplanar bend lines along their edges, which mutually coplanar bend lines are located in a plane which slopes relative to said predetermined direction or which mutually coplanar bend lines are not uniformly in a single plane, whereby at least some cross sections of said part taken along parallel, transverse planes within said at least one section differ along the length of said at least one section, said method comprising the steps of: forming said longitudinally-extending surface portions of said at least one section in said blank between a pair of elongate mandrels having confronting blank-engaging surfaces conforming to said surface portions of said at least one section by pressing said mandrels toward one another into engagement with said blank while it is flat with sufficient force to initiate the forming of said at least one section of said part, and   thereafter completing the roll-forming of said part by passing said blank and said mandrels through a series of passes of said roll forming machine constructed to roll-form said part.   
     
     
       2. The method of claim 1 wherein said at least one section comprises a joggle. 
     
     
       3. The method of claim 1 wherein said roll-formed part comprises a hat section having a centrally located top wall, said surface portions of said at least one section being in said top wall, wherein said blank comprises an elongate strip of sheet metal, and wherein said surface portions of said at least one section are formed in the middle of said strip. 
     
     
       4. The method of claim 3 wherein said at least one section comprises a joggle. 
     
     
       5. The method of claim 4 wherein said forming step comprises providing a first mandrel of said pair of mandrels with a clamping surface having a protrusion projecting therefrom, providing a second mandrel of said pair of mandrels with a clamping surface having a recess therein complementary to said protrusion, assembling said mandrels and said blank with said blank between said mandrels and engaged by said clamping surfaces thereof and with said protrusion confronting said recess, and wherein said pressing step comprises clamping said mandrels to said blank between said protrusion and said recess into said recess. 
     
     
       6. The method of claim 5 wherein said completing step comprises progressively bending portions of said blank adjacent the portions thereof confined between said mandrels against surfaces of one of said mandrels. 
     
     
       7. The method of claim 1 wherein said at least one section comprises a protrusion. 
     
     
       8. The method of claim 3 wherein said at least one section comprises a protrusion. 
     
     
       9. The method of claim 8 wherein said forming step comprises providing a first mandrel of said pair of mandrels with a clamping surface having a protrusion projecting therefrom, providing a second mandrel of said pair of mandrels with a clamping surface having a recess therein complementary to said protrusion, assembling said mandrels and said blank with said blank between said mandrels and engaged by said clamping surfaces thereof and with said protrusion confronting said recess, and wherein said pressing step comprises clamping said mandrels to said blank with sufficient pressure to force the portion of said blank between said protrusion and said recess into said recess. 
     
     
       10. The method of claim 8 wherein said completing step comprises progressively bending portions of said blank adjacent the portions thereof confined between said mandrels against surfaces of one of said mandrels. 
     
     
       11. The method of claim 1 wherein said at least one section comprises a sloping surface. 
     
     
       12. The method of claim 3 wherein said at least one section comprises a sloping surface. 
     
     
       13. The method of claim 12 wherein said forming step comprises providing a first mandrel of said pair of mandrels having a clamping surface having a sloping surface portion, providing a second mandrel of said pair of mandrels having a clamping surface having a complementary sloping surface portion, assembling said mandrels and said blank with said blank between said mandrels and engaged by said clamping surfaces thereof and with said complementary sloping surface portions confronting one another, and wherein said pressing step comprises clamping said mandrels to said blank with sufficient pressure to force the portion of said blank to conform to said sloping surface portions. 
     
     
       14. The method of claim 12 wherein said completing step comprises progressively bending portions of said blank adjacent the portions thereof confined between said mandrels against surfaces of one of said mandrels. 
     
     
       15. The method of claim 1 wherein said completing step comprises progressively bending portions of said blank adjacent the portions thereof confined between said mandrels against surfaces of one of said mandrels. 
     
     
       16. The method of claim 15 wherein each of said passes comprises a forming roll assembly, and said method further comprises constructing said forming roll assembly of at least one of said passes with a forming roll that can move toward and away from said blank and said mandrels when said blank and said mandrels pass through said at least one of said passes, and biasing said forming roll toward said blank and said mandrels. 
     
     
       17. The method of manufacturing an elongate roll-formed part from a flat metal blank using a roll forming machine constructed to roll-form said part by progressively bending said blank about bend lines, said machine having a series of passes along which the blank being formed is driven in a predetermined direction, said roll-formed part having at least one section having longitudinally-extending surface portions, said surface portions having mutually coplanar bend lines along their edges, which mutually coplanar bend lines are located in a plane which slopes relative to said predetermined direction or which mutually coplanar bend lines are not uniformly in a single plane, whereby at least some cross sections of said part taken along parallel, transverse planes within said at least one section differ along the length of said at least one section, said method comprising the steps of: forming said longitudinally-extending surface portions of said at least one section in said blank between a pair of mandrels having confronting blank-engaging surfaces conforming to said surface portions of said at least one section by pressing said mandrels toward one another and said blank while it is flat to initiate the forming of said at least one section of said part, said pressing being accomplished by constructing a first pass of said roll forming machine to provide an orifice sized to receive said mandrels and said blank when assembled and to clamp said blank between said mandrels, and passing said blank and said mandrels through said first pass, and   thereafter completing the roll-forming of said part by passing said blank and said mandrels through a series of passes of said roll forming machine constructed to roll-form said part.   
     
     
       18. The method of claim 17 wherein said mandrels and said blank are passed as a unitary workpiece through said first pass and said series of passes in one continuous operation. 
     
     
       19. The method of claim 18 wherein said completing step comprises progressively bending portions of said blank adjacent the portions thereof confined between said mandrels against surfaces of one of said mandrels. 
     
     
       20. The method of claim 17 wherein said at least one section comprises a joggle. 
     
     
       21. The method of claim 17 wherein said at least one section comprises a protrusion. 
     
     
       22. The method of claim 17 wherein said at least one section comprises a sloping surface. 
     
     
       23. The method of claim 17 wherein aid roll-formed part comprises a hat section having a centrally located top wall, said surface portions of said at least one section being in said top wall, wherein said blank comprises an elongate strip of sheet metal, and wherein said surface portions of said at least one section are formed in the middle of said strip. 
     
     
       24. The method of claim 23 wherein said at least one section comprises a joggle. 
     
     
       25. The method of claim 23 wherein said at least one section comprises a protrusion. 
     
     
       26. The method of claim 23 wherein said at least one section comprises a sloping surface. 
     
     
       27. The method of claim 17 wherein said completing step comprises progressively bending portions of said blank adjacent the portions thereof confined between said mandrels against surfaces of one of said mandrels. 
     
     
       28. The method of claim 27 wherein each of said passes comprises a forming roll assembly, and said method further comprises constructing said forming roll assembly of at least one of said passes with a forming roll that can move toward and away from said blank and said mandrels when said blank and said mandrels pass through said at least one of said passes, and biasing said forming roll toward said blank and said mandrels. 
     
     
       29. A mutually cooperating pair of elongate forming mandrels for clamping a sheet metal blank and supporting the blank during passage in a predetermined direction between forming rolls of a roll forming machine to produce a one-piece, elongate roll-formed part having at least one longitudinally-extending section having longitudinally-extending surface portions, said surface portions having mutually coplanar bend lines along their edges, which mutually coplanar bend lines are not uniformly in a single plane, whereby at least some cross sections of said roll-formed part taken along parallel, transverse planes within said at least one section differ along the length of said at least one section, each of said forming mandrels having longitudinally-extending part-forming surfaces contoured to form parts of said roll-formed part including said at least one longitudinally-extending section and each of said forming mandrels having longitudinally-extending roll-engaging surfaces engageable, respectively, by upper and lower forming rolls at passes of said roll forming machine used to progressively bend said blank about said mutually coplanar bend lines, said part-forming surfaces of each of said forming mandrels including a longitudinally-extending clamping surface, said clamping surfaces of said mandrels clamping the sheet metal blank under pressure between them during the forming of said roll-formed part and being contoured to form said longitudinally-extending surface portions of said at least one section, and   said roll-engaging surface of one of said mandrels having a contour substantially identical to the contour of said clamping surface of the other of said mandrels.   
     
     
       30. A pair of mandrels as in claim 29 comprising: a joggle-forming protrusion extending from the clamping surface of one of said mandrels;   a facing complementary joggle-forming recess in the clamping surface of the other of said mandrels;   said joggle-forming recess and said joggle-forming protrusion constructed to form a joggle in said sheet metal blank when said blank is clamped between said clamping surfaces.   
     
     
       31. A pair of mandrels as in claim 29 comprising: a protrusion-forming recess in the clamping surface of one of said mandrels;   a facing complementary protrusion-forming protrusion extending from the clamping surface of the other of said mandrels;   said protrusion-forming recess and said protrusion-forming protrusion constructed to form a protrusion in said sheet metal blank when said blank is clamped between said clamping surfaces.   
     
     
       32. A mutually cooperating pair of elongate forming mandrels for clamping a sheet metal blank and supporting the blank during passage in a predetermined direction between forming rolls of a roll forming machine to produce a one-piece, elongate roll-formed part having at least one longitudinally-extending section having longitudinally-extending surface portions, said surface portions having mutually coplanar bend lines along their edges, which mutually coplanar bend lines are located in a plane which slopes relative to said predetermined direction, whereby at least some cross sections of said roll-forward part taken along parallel, transverse planes within said at least one section differ along the length of said at least one section, each of said forming mandrels having longitudinally-extending part-forming surfaces contoured to form parts of said roll-formed part including said at least one longitudinally-extending section and each of said forming mandrels having longitudinally-extending roll-engaging surfaces engageable, respectively, by upper and lower forming rolls at passes of said roll forming machine used to progressively bend said blank about said mutually coplanar bend lines, said part-forming surfaces of each of said forming mandrels including a longitudinally-extending clamping surface, said clamping surfaces of said mandrels clamping the sheet metal blank under pressure between them during the forming of said roll-formed part and being contoured to form said longitudinally-extending surface portions of said at least one section, and   said roll-engaging surface of one of said mandrels having a contour substantially identical to the contour of said clamping surface of the other of said mandrels.   
     
     
       33. A pair of mandrels as in claim 32 comprising; a joggle-forming protrusion extending from the clamping surface of one of said mandrels;   a facing complementary joggle-forming recess in the clamping surface of the other of said mandrels;   said joggle-forming recess and said joggle-forming protrusion constructed to form a joggle in said sheet metal blank when said blank is clamped between said clamping surfaces.   
     
     
       34. A pair of mandrels as in claim 32 comprising: a protrusion-forming recess in the clamping surface of one of said mandrels;   a facing complementary protrusion-forming protrusion extending from the clamping surface of the other of said mandrels;   said protrusion-forming recess and said protrusion-forming protrusion constructed to form a protrusion in said sheet metal blank when said blank is clamped between said clamping surfaces.   
     
     
       35. Apparatus for producing a roll-formed part from an elongate strip of sheet metal, said apparatus comprising a roll forming machine having a series of passes of forming roll assemblies along which the strip is driven in a predetermined direction, said roll-formed part having at least one longitudinally-extending section having longitudinally-extending surface portions, said surface portions having mutually coplanar bend lines along their edges, which mutually coplanar bend lines are located in a plane which slopes relative to said predetermined direction or which are not uniformly in a single plane, whereby at least some cross sections of said part taken along parallel, transverse planes within said at least one section differ along its length, said apparatus comprising a pair of elongate mandrels each having a clamping surface shaped to conform to the desired final configuration of first surface portions of said roll-formed part that include said longitudinally-extending surface portions of said at least one longitudinally-extending section so that said mandrels and said strip may be assembled together with said strip engaged by and confined between said clamping surfaces of both of said mandrels, one of said mandrels having second surface portions shaped to conform to the desired final configuration of other surface portions of said roll-formed part, each of said forming roll assemblies including rolls used to progressively bend said strip about said mutually coplanar bend lines, which rolls are shaped to provide an orifice through which said mandrels with said strip confined therebetween may pass, the orifice of one of said forming roll assemblies being shaped to clamp said mandrels to said strip with sufficient pressure to force the contour of said first surface portions of said strip to be formed into conformity with the contours of said clamping surfaces of said mandrels as said mandrels and said strip enter said one of said passes, the shapes of said orifices of at least some of said passes being different from other passes so that the transverse cross-sectional configuration of said strip is progressively changed as said strip moves through said successive passes by the progressive formation of portions of said strip into engagement with said second surface portions of said one of said mandrels. 
     
     
       36. The apparatus of claim 35 wherein said forming roll assemblies include rolls shaped to drivingly engage said mandrels to cause said mandrels with said strip confined therebetween to move through said successive passes. 
     
     
       37. The apparatus of claim 35 wherein said forming roll assemblies each includes an upper forming roll and a lower forming roll, and wherein at least some of said roll assemblies include means biasing one of said upper and lower rolls toward the other of said upper and lower rolls. 
     
     
       38. The apparatus of claim 37 wherein either the upper or the lower one of said forming rolls of at least one of said forming roll assemblies has roll surfaces contoured to engage one of said mandrels and the part being formed which roll surfaces have the same contour as the corresponding roll surfaces of a corresponding roll of a preceding one of said forming roll assemblies. 
     
     
       39. The apparatus of claim 38 wherein the other of the upper and lower forming rolls of said last mentioned at least one of said forming roll assemblies has roll surfaces contoured differently from the corresponding roll of said preceding one of said forming roll assemblies. 
     
     
       40. The apparatus of claim 35 wherein one of said mandrels has a roll-engaging surface facing opposite to its said clamping surface, said roll-engaging surface having a contour matching the contour of said clamping surface of the other one of said mandrels. 
     
     
       41. The apparatus of claim 40 wherein said forming roll assemblies each includes an upper forming roll and a lower forming roll, and wherein at least some of said roll assemblies include means biasing one of said upper and lower rolls toward the other of said upper and lower rolls. 
     
     
       42. The apparatus of claim 41 wherein either the upper or the lower one of said forming rolls of at least one of said forming roll assemblies has roll surfaces contoured to engage one of said mandrels and the part being formed which roll surfaces have the same contour as the corresponding roll surfaces of a corresponding roll of a preceding one of said forming roll assemblies. 
     
     
       43. The apparatus of claim 42 wherein the other of the upper and lower forming rolls of said last mentioned at least one of said forming roll assemblies has roll surfaces contoured differently from the corresponding roll of said preceding one of said forming roll assemblies.